1. Field of the Invention
The present invention relates to a device and method for wide-field and high resolution imaging. Particularly, the present invention is directed to a system having wide-field and high resolution imaging capability.
The present invention is particularly suitable for imaging skin cancer, e.g., as a rapid bedside guide to tumor excision. The invention is useful for providing enhanced imaging of epithelial tumors, inflammatory disorders, or other pathological conditions, including nonmelanoma skin cancer. However, the subject device and method may be used for imaging and analyzing surface, structural, spectral, functional, fluorescence, Raman, bio-chemical, polarization and other similar characteristics of any object when the combination of wide field imaging and high resolution is required.
2. Description of Related Art
Advances in the development of optical imaging modalities have facilitated efforts to employ these techniques for noninvasive detection and treatment guidance of different pathological conditions. In general, the turbidity of tissue creates major challenges for optical in vivo spectroscopy and imaging. However, reflectance and fluorescence imaging techniques, like multi-spectral polarized light macro-imaging and confocal microscopy are well suited for skin cancer detection and demarcation. Confocal reflectance microscopy was introduced to the field of dermatology in the 1990s. Since then, it has been used to study different skin disorders.
Confocal microscopy is a technique where the specimen is pointwise illuminated by a focused beam of light. An image is recorded by scanning the beam focus through a plane in the specimen, and the reflected light from the specimen is focused onto a small detector aperture. The light source, the illuminated spot and the detector aperture are placed in optically conjugated focal planes. “Optical sectioning” occurs as out-of-focal-plane back-scattered light is rejected by a pinhole placed in front of a detector. Optical sectioning makes it possible to record images of thin layers within tissue. Confocal microscopy allows imaging within turbid media with high resolution (lateral resolution of about 1 μm, and axial resolution (section thickness) of about 3-5 μm), which is comparable to histology. The major disadvantage of confocal microscopy as a detection and guidance tool for cancer surgery is its small field of view, which is typically, up to about 0.3 mm. To examine an entire suspected cancerous area using confocal microscopy (CM), a sequence of images must be captured and stitched together. This process takes time and motion artifacts may distort the resulting image.
Multi-spectral polarized light imaging (MSPLI) is a simple and inexpensive technique for skin tumor imaging. The technique provides the means to differentiate effectively between endogenous (blood, melanin, etc.) and exogenous (dye) chromophores absorbing in different spectral domains, and is capable of obtaining superficial images (at a resolution of about 3-50 μm-lateral, 5-0200 μm-axial in the visible spectral range) of thick tissue layers. Such imaging is relatively insensitive to small shifts in the position of the imaged object, and combination of the large field-of-view and sufficient lateral resolution enables rapid examination of large surfaces, thus facilitating tumor margin delineation. However, morphology of individual cells and fine structures cannot be resolved using MSPLI. Thus, the multi-spectral polarized light imaging approach can benefit from combination with a high-resolution technique, such as confocal reflectance microscopy, which can be used by a pathologist in the cases when high-resolution images of small suspicious areas are required. Such combination may become a powerful tool for cancer detection and demarcation.